Patchable +Constants: KListImplBufferSize

diff -r 4816d766a08a -r f345bda72bc4 Symbian3/PDK/Source/GUID-2EE70A59-7EF0-5A1B-986B-00ED5ACD8BD4.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Symbian3/PDK/Source/GUID-2EE70A59-7EF0-5A1B-986B-00ED5ACD8BD4.dita Tue Mar 30 11:56:28 2010 +0100 @@ -0,0 +1,64 @@ + + + + + +Patchable +Constants: KListImplBufferSize +# define ECOM_PATCHDATA_KLISTIMPLBUFFERSIZE 2048 + + + + +

Exported from:

ECOMPATCHDATA.DLL

+ + +

Defined in:

.../os/ossrv/lowlevellibsandfws/pluginfw/framework/frame/ecompatchdataconstant.cpp

+ + +

Purpose:

This constant is used to define the size of the buffer that is pre-allocated +on the ECOM client side to hold the list of Implementation Information records. +The records are copied from the server as a result of a call to one of the REComSession::ListImplementationsL() functions.

If the result of a call to ListImplementationsL() does +not fit into the initial buffer, the server stores the result and tells the +client the required size. ListImplementationsL() then reallocates +the buffer and makes a second call to the server to retrieve the results.

This +value can be adjusted during ROM build time to suit a particular device. In +general, a smaller value results in more client-server requests, while a larger +value results in fewer client-server requests. Care must be taken when choosing +the value. A large value, increases the temporary heap consumption by ECOM +client processes, but results in faster completion of the call to ListImplementationsL() because +of fewer client-server calls. System start-up can benefit from fine-tuning +this value.

The default size is 2048 bytes. This value optimises performance +on the Symbian test UI platform. Larger values do not result in any significant +gain in performance; smaller values reduce performance.

To work out +the optimum value for this constant, you need to discover the typical size +of the buffer required for each call to ListImplementationsL(). +To get such values, you need to enable the ECOM_TRACE macro +and rebuild ECOM. After booting up the device, you will see +output in the following format from the serial port:

ECOM ListImplementations request buffer size required=88 ECOM ListImplementations request buffer size required=1562

You +can use this information to calculate mean and median values, which will help +you to choose the optimum value for your platform.

+ + + +

ECom uses a customized scheme to handle patchable constants. Device creators +should follow the scheme described below to set patch values:

Each patchable constant +is represented by a macro listed in \epoc32\rom\include\ecompatchconstants.hby. +The macros in the HBY file are all commented out.
To activate a patch +macro, uncomment the line and change the example value in the line to your +custom value.

+ \ No newline at end of file